Ground Plane split for GSM engine, a SLIC , a DAA and a CODEC

[cesare]

Hi All,

I'm desgning a board containing a GSM engine, a SLIC , a DAA and a CODEC.

The SLIC, the DAA and the CODEC are mixed signal devices that contains an A/D and a D/A and the manufacturer of this silicon reccomends the use of a separate analog and digital ground joined under the IC body. Obviously this reccomendation is aimed to maximize IC performance.

If I follow these reccomandations my ground plane will be separated in several small ground planes.

But in my design I have also to face with RF ! This device uses a monopole antenna directly connected to the PC Board and so the ground plane will be directly involved in RF radiation.

In this case I'm afraid that the different ground planes will behave as small dipoles and cause troubles. My opinion is that a solid unsplitted ground plane should be better for RF but what about mixed signal IC ?

I have read several articles and forum topics on how to split (or not to split) the ground plane and how to route the traces but no one of them faces directly my problem

Can someone give me some hint on the best solution in this case ?

Thanks in advance

 

[biff44]

Re: Ground Plane Split

I apreciate your agressivness in trying to layout this printed wiring board. But seriously, you need to hire an experienced microwave engineer to advise you. You can try it on your own, and 5 or so tries later you might get it to marginally work! With an microwave engineer, you probably will get usable product on the first pass, saving schedule time, money, and averting missed opportunities.